In the case of valves, and more particularly multiway valves with a piston- or spool-like valve member located in a receiving recess, there are particular problems related to wear. In order to provide a sealing effect between the valve member and the housing part of the valve defining the recess, it is necessary to provide sealing rings held on the valve member or on the valve housing part so as to surround the valve member and which in operation have to perform relative motion, while contacting the respectively other element, with respect to the latter. Since on the valve member or a part thereof in sliding contact with the respective sealing ring there are generally grooves, ledges, shoulders, ports of ducts and the like in the form of irregularities in the surface, there is pronounced wear on the sealing ring where it makes contact with the edges of such interruptions in the surface. The resulting impairment of the surface of the sealing ring leads to a reduction in the ability of the sealing ring to perform its function so that frequent replacement of the sealing ring and interruptions in operation of the valve are necessary.